ABSTRACT In response to the Notice of Special Interest (NOSI) regarding the Availability of Administrative Supplements and Urgent Competitive Revisions for Research on the 2019 Novel Coronavirus (Notice Number NOT-DA-20-047 and linked Program Announcement PA-18-591) funding opportunity, the Collaborating Consortium of Cohorts Producing NIDA Opportunities (C3PNO; U24DA044554) proposes a project to assess the impact of COVID-19 on the participating cohorts' population of substance-using people living with HIV (PLWH) and those at high-risk for HIV infection. Our innovative study proposes to collect data from a subset of participants from each of seven participating C3PNO cohorts at two time points ? in the height of the COVID-19 pandemic and during its mitigation and control ? in order to assess the impact of the COVID-19 epidemic on substance use for PLWH and those at high risk for HIV. We will use our current infrastructure and C3PNO validated harmonization strategies to compile new and existing data across the cohorts in order to: assess changes in social and individual determinants of health during the course of the COVID-19 pandemic, to estimate differences in substance-using behaviors of those who were confirmed/probable cases of COVID-19 (based on self-report or medical record) and those who were not a confirmed/probable case, and to assess how PLWH and people who are at high risk for HIV in C3PNO have different experiences in and responses to the COVID-19 epidemic as compared to other HIV studies and cohorts that have less substance use. The C3PNO Coordinating Center at UCLA and Frontier Science will facilitate the design and implementation of a survey to collect data from a subset of participants from each of seven participating C3PNO cohorts (ALIVE, HYM, JHHCC, MASH, mSTUDY, RADAR, and V-DUS). Participating cohorts will issue the survey to participants and transfer the resulting data to the coordinating center. If funded, this administrative supplement would allow a rapid and coordinated collection of linked COVID-19, HIV, and substance use data related to an ongoing public health emergency affecting the highly vulnerable substance-using populations followed by the cohorts. COVID-19 data harmonization with other HIV cohorts will further aide our collective effort to understand the impact of COVID-19 on HIV impacted communities. Finally, C3PNO's effort to assess changes in social and individual determinants of health during the course of the COVID-19 pandemic as well as estimate differences in substance-using behaviors and the impact on PLWH or at high risk for HIV is both novel and critical in this time of unprecedented social upheaval and instability.